Spark plug



July 1923.

J. S. SOLOMON SPARK PLUG Filed Dec. 16 1920 I 1 m M 1' I .W: 0 m g O.) u M A N V w J00 e gh S uwlz I all Patented July 10, 1923.

UNITED STATES PATENT OFF! To all whom it may concern:

Be it known that I, Josnrn Simon Sow' you, a citizen of the United States, and a resident of Evansville, in. the county of Vanderburgh 'and Statc of Indiana, have invented certain new and useful Im' rovements in Spark Plugs, of which the allowin is a specification.

y invention relates to s ark plugs and a purpose of my invention is e provision of a spark plug comprising a plurality of electrodes permanently adjusted and arran to provide a succession of spark gaps which function to intensify the s ark m the aggregate and to prevent fouling of the plug.

I will describe one form of spark plug embodying my invention and will then point out the novel features thereof in claims.

In the accompanyin drawings:

Figure 1 is a view a owing in side elevation one form of spark plug embodying my invention.

Fl 2 is a vertical longitudinal sectional view of the spark plug shown in Figure 1.

Figure 3 is an enlarged detail view showing in vertical section the lower end of the spark lug in applied sition within the head 0 an internal com ustion engine.

Referring specifically to the drawings, my invention in its present embodiment consists of a standard form of sleeve S ada ted to threadedlv fit within the usual spar plug openin formed in the head of a cylinder, such 5 eeve being interior-1y provided with an annular shoulder 15 against which rests the lower edge of a circular projection 16 formed intermediate the ends of an insulating tube T which extends throu the sleeve in the manner shown in Fi A asket 17 is inter d between tie lower go of the projection 16 and the shoulder 15'. The normal diameter of the tube T is les than the internal diameter ofthe sleeve S, and after locking the tube in enga 'ng position with respect to the shoulder 15, provide the usual bushing B threadedly fitted within the upper end of the sleeve S and e cable with the upper edge of the projection 16, a gasket 19 being interposed between the two.

The tube T receives a stem 20, the upper end of the latter being provided with a binding nut 21, a washer 22 and a nut 23 inter-. posed between the two and all coactnnafitgl sustain the stem in proper position W1 .between the the tube and to provide the usual binding post for connecting the conductor to the spark plug. The lower end of the stem 20 is formed with a main electrode 24 which is of substantially stantiall the tube That portion of the tube '1 progicting beyond the lower end of the sleeve is formed with a. plurality of circular grooves 25 spaced apart at from each other and from trode 24. Within each subsidiary electrode 26, having; shown in the present instance five grooves and five subsidiary electrodes, although it is to be understood that any number of grooves and electrodes may be provided. The arrangement of the electrodes 26 with act to each other and to the main electro e 24 is such that an annular spark gap is rovided electrodes, each gap ing of uniform width throughout its circumference so as to provide a uni orm resistance between the electrodes. As shown in Fi res 2 and 3, the uppermost electrode 26 is disposed adjacent the head of the cylinder so that the two coact to provide another air gap across which the spark is adapted to jump.

From the foregoing arrangement of electrodes, it will be clear that a circuit is established which may be chased as follows: from the stem '20 downwardly to and through the main electrode 24, through the several subsidiary electrodes 26 and finally through the sleeve Sto ground. From this circuit it will,- be seen that the current is caused to successively jump the gaps between 311: elgct-rodes 24 and 26 of. this! sleeve S, and

t e current in jumpingsee an generates a plurality of circular sparks vhich increase in intensity from the lowermost gap to the uppermost gap.

In the manufacture of the spark plug, the several subsidiary electrodes 26 are spaced a redetermined distance from each other, and after this adjustment has been once made it is always maintained irrespective of the rough usage to which the plug may be subsequently subjected. Because of the circular sparks occurring be tween any two adjacent electrodes it will be manifest that the accumulation of carbon between the electrodes is rovented, and that should carbon aocumul between the uppermost electrode 26 and the lower end of huintervals 9 main elecoove is fitted a.

disc formation and of sub-s the same diameter as the and of the sleeve S, this short circuiting of this particular electrode will not prevent the operation of the other electrodes.

Although I have herein shown and described only one form of spark plug embodying my invention, it is to be undeistood that various changes and modifications may be made herein without departing from the spirit of the invention and the spirit and scope of the appended claims.

What I claim is:

1. A spark plug comprising a metallic sleeve, having an annular shoulder extending inwardly from the inner wall thereof at an a. preciable distance from the lower end, a tu e of insulating material embraced by the portion of the sleeve located above the said shoulder and having the lower portion thereof spaced from the confronting portion of the inner wall of the metallic sleeve in such manner as to provide an annular air gap extending for an appreciable distance from the lower end of the metallic sleeve, said tube being of suflicient length to ,depend below the lower end of the sleeve, a stem extending through the tube, means at the upper end of the stem for sustaining the stem within the tube, a main electrode secured to the lower end of the stem, and a lurality of auxiliary electrodes seated within the periphery of the depending end of the tube, the auxiliary electrodes being spaced apart from one another and from the main e ectrodes by integral portions of the insulating tube, with the uppermost auxiliary electrode arranged in spaced relation to the lower end 0 said sleeve to provide a spark gap and with the peripheral face of each auxiliary electrode flush with the peripheral faces of the adjacent portions of the insulating tube.

2. A. spark plug comprising a metallic sleeve, 8. tube of insulating material extendmg through the bore of the sleeve and hav ing its lower end projected beyond the lower end of the sleeve, said tube hein formed with the lower end portion thereo smaller diametrically than the inner diameter of the lower portion of the sleeve and being spaced from the latter to provide an annular air p extending for an appreciable distance rom the lower end of the metallic sleeve, a stem extending through the tube, means at the upper end of the stem for sustaining the latter within the tube, a main electrode secured to the lower end of the stem, and a plurality of auxiliary electrodes seated within the periphery of the projecting end of the tube and being spaced from one another by integral vportions of the insulating tube, the uppermost auxiliary electrode being spaced from the lower end of the metallic sleeve to provide a spark gap therebetween, and the peripheral faces of the auxiliary electrodes being flush with the peripheral faces of the spacing portions of the insulating tube.

J O EPH SIMON SOLOMON. 

